roasting drum material is what, regular iron, stainless, or cast iron?

cast iron has a high thermal mass, which means longer heat but longer cold and much more stable. stainless and more responsive to the changing heat input, meaning more precision for control but more demanding skills. steel used to be more of a cheaper entry class.

from the coffee side, the drum material is not as big as it claims. much greater influence is the design and thickness of the drum, how the heat distribution is in the drum, and of course the profile is run.

durability: stainless more corrosive and easier to clean. cast iron is heavier but can last very long if treated properly. the regular iron is the easiest to rust and needs more maintention.

that material selection is one of many engine design factors. not too fixed on material only if it's a machine compare, see also airflow system, insulation, convenience ease, and support after sales of brand.